Archive for category metrology
Image Analysis with (free) ImageJ software
Posted by Michael Beach in metrology, optics, tools on June 29th, 2009
Lately we’ve been able to use our digital camera to perform some nice measurements, through the help of a program called ImageJ.
It’s free, was developed at NIH, is open-source, it has a ton of features and plug-ins, and you can write scripting macros, etc etc. It was developed so that the scientific community would have an open standard to process images. (Without an open standard for image number crunching, there’s no good way to independently reproduce an experiment that makes heavy use of images and image processing.)
You can read about it here at Wikipedia:
link to wiki entry for ImageJ program
http://en.wikipedia.org/wiki/ImageJ
It’s available here:
http://rsbweb.nih.gov/ij/
We were turned onto this image analysis program by a couple of our clients. We recommend it. Today the cool thing was to separate the RGB channels, and allow us to ‘see’ an IR LED without being confused by the camera’s ‘grey scale’ clipping algorithm. Very nice.
CCD Cameras, eyes, and physics
Posted by Michael Beach in application notes, how-to, math, metrology, optics, tech notes, technical articles on March 14th, 2009
This tech note was motivated by the question – how does the response of our eyes
differ from the response of a CCD camera sensor.
Using the data of a particular Hammamatsu CCD camera as an example,
we compared how silicon ‘sees’ to the photopic eye response
and compared both to a Planck black-body curve of a light at a particular
color temperature.
We don’t know what those lumps are in that CCD response curve – maybe some
strange reflection interference??
If you know – tell us!
Vision response vs. Planck’s Black Body Curve
Posted by Michael Beach in application notes, how-to, math, metrology, optics, tech notes, technical articles on March 14th, 2009
Color temperature is based upon the idea of a Planck black-body radiator.
Here’s a Tech Note that shows how our eyes respond to the Planck Black-Body radiator.
For a lamp filament at a certain ‘color temperature’ there’s a curve of how our eyes
respond to the lamp. Pete put this into a MathCAD model, and there’s a pdf here
that shows off a few nice graphs.
Actinica Book List
Posted by Michael Beach in application notes, books we like, how-to, math, metrology, optics, research papers, tech notes on May 31st, 2008
Ok, we have a book problem.
Both of us waay like good engineering books. A good explanation, or a great
graph that sums up why that camera ‘sees’ differently than my eyes, etc.
Since we’re always stumbling on more good books, this list will grow.
Drop by later see what’s new.
Here’s some of the books we like, as a pdf file here,
and here’s some more books we like:
- the Feynman Lectures on Physics, a 3 volume set. Here’s a guy who can explain anything well. Like how sine, cosine and the magic number e all relate to the imaginary number i (square root of -1). He also has a great description of how a ’50 Ohm’ transmission line acts like ’50 Ohms’ no matter how long it is. For a really great puzzle – read his description of how charging a capacitor really involves magnetic fields outside the cap’s plates.